Have her go on Amazon and download all the songs at .99-1.29 a piece; then go to her local rental house to get a sound system if she is that concerned with price. Even there...she's still looking at probably $200 for a second rate job and no dedicated emcee or good way to handle requests.
I have had brides ask me for copies of their playlists on burned Cds. I always decline this request as it is illegal. I have had some pushback (as some of my competitors allegedly have made the Cds), and normally retort with something along the lines of I am happy to provide them with a text export of what was played, however, if they would like to give me a gift card to a music downloading site and thirty dollars an hour for my time, I will gladly download dedicated copies of their songs for them. This usually squashes it pretty fast.